Generation of α-Boryl Radicals by H Transfer and their Use in Cycloisomerizations.

Carbon-centered radicals can be stabilized by delocalization of their spin density into the vacant p orbital of a boron substituent. α-Vinyl boronates, in particular pinacol (Bpin) derivatives, are excellent hydrogen atom acceptors. Under H , in the presence of a cobaloxime catalyst, they generate α-boryl radicals; these species can undergo 5-exo radical cyclizations if appropriate double bond acceptors are present, leading to densely functionalized heterocycles with tertiary substituents on Bpin.

H· Transfer-Initiated Synthesis of -Lactams: Interpretation of Cycloisomerization and Hydrogenation Ratios.

A cobaloxime/H system used to synthesize valuable -lactams from acrylamide molecules is described. In addition to cycloisomerized lactams, linear hydrogenated products were also observed. The amounts of the hydrogenation product were observed to correlate with the bulk of the substituent on the acrylamide nitrogen.

Synthesis, Structure, and Bonding of d Molybdenum-Oxo Complexes.

Reduction of d metal-oxo ions of the form [MO(PP) Cl] (M=Mo, W; PP=chelating diphosphine) produces d MO(PP) Cl complexes, which include the first isolated examples in group 6. The stability and reactivity of the MO(PP) Cl compounds are found to depend upon the steric bulk of the phosphine ligands: derivatives with bulky phosphines that shield the oxo ligand are stable enough to be isolated, whereas those with phosphines that leave the oxo ligand exposed are more reactive and observed transiently. Magnetic measurements and DFT calculations on MoO(dppe) Cl indicate the d compounds are low spin with a [(d ) (π*(MoO)) ] configuration.

Accelerating sample preparation through enzyme-assisted microfiltration of Salmonella in chicken extract.

Microfiltration of chicken extracts has the potential to significantly decrease the time required to detect Salmonella, as long as the extract can be efficiently filtered and the pathogenic microorganisms kept in a viable state during this process. We present conditions that enable microfiltration by adding endopeptidase from Bacillus amyloliquefaciens to chicken extracts or chicken rinse, prior to microfiltration with fluid flow on both retentate and permeate sides of 0.2 μm cutoff polysulfone and polyethersulfone hollow fiber membranes.

Varying substituents and solvents to maximize the luminescence from [Ru(trpy)(bpy)CN]+ derivatives.

Ruthenium(II) in combination with monodentate, bidentate, and tridentate ligands has proven to be a useful design for a variety of applications, but the majority of systems are virtually nonluminescent in solution. The goal of this work has been to design luminescent forms with practicable emission quantum yields, and the focus has been on [Ru(X-T)(dmeb)CN](+) systems, where X-T denotes 2,2':6',2″-terpyridine bearing substituent X at the 4'-position and dmeb denotes [2,2'-bipyridine]-4,4'-dicarboxylic acid, dimethyl ester. Results show that varying the π-electron-donating ability of the 4'-X substituent is an effective way to tune the energy and lifetime of the charge-transfer (CT) emission.

Rapid sample processing for detection of food-borne pathogens via cross-flow microfiltration.

This paper reports an approach to enable rapid concentration and recovery of bacterial cells from aqueous chicken homogenates as a preanalytical step of detection. This approach includes biochemical pretreatment and prefiltration of food samples and development of an automated cell concentration instrument based on cross-flow microfiltration. A polysulfone hollow-fiber membrane module having a nominal pore size of 0.

Dihydrogen activation by a tungsten-alkylidyne complex: toward photoredox chromophores that deliver renewable reducing equivalents.

The d(1) tungsten-alkylidyne radical [W(CPh)(dppe)2Cl](+) reacts with H2 to give the d(0) hydride [W(CPh)(H)(dppe)2Cl](+), which on deprotonation yields the d(2) photoredox chromophore W(CPh)(dppe)2Cl. This family of reactions results in a cycle by which renewable H2 provides the reducing equivalents for photochemical reductions.